shellcheck warnings for Arx in branch master

• SC1003 [docs] (1 | =)
• SC1091 [docs] (1 | =)
• SC2119 [docs] (1 | =)
• SC2120 [docs] (1 | =)
• SC2162 [docs] (1 | =)
• SC2059 [docs] (2 | =)
• SC2016 [docs] (3 | =)
• SC2164 [docs] (6 | =)
• SC2154 [docs] (9 | =)
• SC2034 [docs] (15 | =)
• SC2086 [docs] (73 | =)
• SC2317 [docs] (292 | =)